The Po Valley (Northern Italy) represents an important exceedance zone of the air-quality limit values for PM (particulate matter), NO2 (nitrogen dioxide) and O3 (ozone). This area covers the territory of most Italian northern regions and includes several urban agglomerates, such as Milan, Turin, Venice and Bologna. The area is densely populated and heavily industrialized. The paper summarizes the assessment of the impact of the current (2013) and future (2025) emissions and of the meteorological conditions on the air quality of the Po Valley. This study is one of the first outcomes of the EU LIFE-IP Clean Air Program Po Regions Engaged to Policies of Air (PREPAIR) project. The project, involving administrations and environmental agencies of eight regions and three municipalities in Northern Italy and Slovenia, started in 2017 and will end in 2024. Future emission scenarios consider the emissions reduction due to the air-quality action plans of the regions involved, of the agreements between the national authorities and regional administrations and of the PREPAIR project itself, in the overall context of the application of the current legislation of the European Union. The combination of these measures will lead to the reduction of direct emissions of PM10 in the Po Valley and of the main precursors emitted in the area (NOx, nitrogen oxides and NH3, and ammonia) by 38% for PM10, 39% for NOx and 22% for NH3, respectively. This lowering corresponds to a reduction of about 30.000 tons of primary PM10, 150.000 tons of NOx, 54.000 tons of NH3 and 1700 tons of SO2. The results show that these expected reductions should allow us to achieve the EU PM10 limit value in the Po Valley by the year 2025.